Calculating your winter hay supply ahead of time ensures your cow herd stays in optimal body condition without costly mid-winter feed emergencies. Follow these steps to determine your total feed requirements:
- Determine your average mature cow size. This can be done by weighing your 4- to 7-year-old cows and calculating the average weight. From mature cow size, we can approximate the amount of forage dry matter cows will need to consume per year or per day. For example: a 1,000-lb. cow will consume about 26 lb. of forage dry matter per day. A 1,400-lb. cow will consume about 36.4 lb. of forage dry matter per day.
- Determine your cow inventory.
- Estimate the amount of time you expect to be feeding cows.
From this information you can calculate the total amount of hay needed. For example: 100 cows weighing 1,400 lb. will consume about 3,640 lb. of hay per day. We should take into account that a certain amount of the hay fed will be wasted and there will be a certain amount of spoilage of each bale fed that won’t be consumed. With this in mind we will add another 10% to the daily total to bump it up to about 4,000 lb. (2 ton) per day.
Remember the amount of hay wasted or spoiled could be higher. If we are feeding hay from last year expect a higher percentage spoiled in each bale.
If we are expecting to feed hay from mid-October to mid-May, that is approximately 200 days of hay feeding. 4,000 lb. of hay needed per day x 200 days equals a total of 800,000 lb. (400 ton) of forage dry matter that cows will consume over this time.
If we are feeding or buying large rounds with an average weight of 1,250 lb. that equates to 640 (800,000 divided by 1,250) big bales needed to sustain the 100 cows.
If possible, purchase hay by the ton. It leads to less error in securing the amount of hay you will need to purchase or have on inventory. If buying hay by the bale is your only option, make sure to weigh enough of the bales to have an accurate representation of bale weight. Also, take into account the amount of spoilage of each bale. One of the upsides of hay baled this summer (and the drought over the past few months) is less spoilage.
Other factors such as weather, stage of gestation or lactating versus dry cows will obviously impact nutritional requirements of cows from day to day. Provide hay and other nutritional supplementation accordingly.
